docs: def set_monitor(module):
      """ Defines the monitor method on the module. """
      def monitor(name, tensor,
                  track_data=True,
                  track_grad=True):
          """
          Register the tensor under the name given (now a string)
          and track it based on the track_data and track_grad arguments.
          """
          module.monitored_vars[name] = {
              'tensor':tensor,
              'track_data':track_data,
              'track_grad':track_grad,
          }
      module.monitor = monitor